Currently, commercially available contact lenses containing ultraviolet radiation absorbing materials are limited in their ability to block ultraviolet radiation from entering the eye. Further, such contact lenses do not meet American National Standards Institute (ANSI Z80.20-1998) Class 1 specifications for ultraviolet radiation absorption. The ANSI specifications require an average percent transmittance of less than 1 percent at 280 to 315 nanometers (nm) and less than 10 percent at 316 to 380 nm.
In one class of contact lenses, described as hydrogels, it has been difficult to incorporate ultraviolet radiation absorbing materials into these lenses because of their hydrophilic nature and expanded structure. The majority of ultraviolet radiation absorbing materials described in the art are generally hydrophobic and have limited solubility in hydrogels. Further, if the aforementioned ultraviolet radiation absorbing materials are added in excess to the ocular device, the properties, e.g., durability, flexibility, hydrophilicity, stability to sterilizing regimes, etc., of the ocular device can be adversely effected.
Therefore, a need remains for an ocular device that provides not only variable protection to visible light but also protection against ultraviolet radiation.